When you see photos of Cameron Diaz's slim silhouette or Jessica Alba's flat post-pregnancy tummy, you probably wonder just how Hollywood stars stay so lean or snap back into shape so quickly. While many swear their svelte bods come from eating right and exercising round the clock, the truth is that some celebs may go to strange and interesting lengths to get or stay pin thin. Here, the skinny on exactly what the big names do to get red-carpet ready -- from the healthy strategies you'll want to steal to the just plain wacky ideas you'll want to avoid.

Some nutritionists have clients load up on watery veggies, like celery, but avoid gas-prducing ones like broccoli.

1. They eat breakfast

Celebrity trainer Gunnar Peterson (whose clients include Jennifer Lopez, Leah Remini, and Penelope Cruz) recommends popping something into your mouth within 30 minutes of waking. "You want to send your body a sign that you're not starving so it starts burning fat," Peterson says. His suggestion: a cup of oatmeal with some sliced fruit and several scrambled egg whites. The oatmeal and fruit pack a huge punch of filling fiber, and the egg whites are rich in protein, which is satiating.

Verdict: Try it.

Research shows breakfast eaters are more successful at long-term weight loss than those who skip this meal. "It jump-starts your metabolism and prevents you from getting so ravenous you overeat later in the day," says Bonnie Taub-Dix, R.D., a New York City-based spokeswoman for the American Dietetic Association.

2. They cut out white foods

Trainer Teddy Bass, whose celebrity clients include Cameron Diaz, suggests ditching any carb that is white -- bread, pasta, cookies, rice -- when a star is trying to lose weight for a movie or a big event. "These foods are high in sugar, which means your body burns off the sugar first rather than the stored fat," he says. So is Diaz entirely carbophobic? No -- she gets them instead in the form of fruits and veggies.

Verdict: Try it.

It's true that white, processed carbs are high in calories and sugar, so limiting them is a healthy strategy. But don't just sub in a boatload of nonwhite foods. "I see clients who shun these foods but end up eating just as many calories by having a field day with whole-wheat products," Taub-Dix says. "Even if it's a cake made with whole-wheat flour, it's still loaded with calories."

3. They're picky about veggies

A few days before a be-seen event, some Los Angeles nutritionists and trainers tell clients to put gas-producing produce like cauliflower and broccoli on the black list. Nutritionist Carrie Wiatt has Denise Richards and Fergie stock up instead on watery veggies and fruits like lettuce, celery, cucumbers, watermelon, melon, oranges, and grapes, which help banish bloat by flushing out your system. And L.A. nutritionist Jackie Keller tells clients like Charlize Theron to pile their plates high with asparagus and green beans. "They're high in filling fiber, but less likely to expand in your stomach," Keller says.

Verdict: Try it.

Produce like broccoli, cauliflower, cabbage, Brussels sprouts, onions, beans, apples, pears, and prunes do lead to gas and bloating, says Jennifer Crum, M.S., R.D., a nutritionist at New York University Langone Medical Center. Crum also suggests cutting out diet drinks before a big event, since carbonation and artificial sweeteners can lead to bloat. Dandelion tea, a diuretic, is a safe drink option, Taub-Dix says. Don't like the bitter taste? Try peppermint or chamomile, which have a similar effect. Health.com: Survive the holidays (without gaining weight)

4. They eat spicy

Supermodel trainer David Kirsch helps clients like Anne Hathaway and Liv Tyler stay in great shape by pushing them to add red pepper flakes, chopped jalapeños, and hot pepper sauce to their meals. "It makes food taste delicious and turns down hunger, so you eat less," he says.

Verdict: Try it.

A study out of Laval University in Quebec found that people who consumed hot red pepper ate less food and burned more calories (probably because the pepper increased their metabolism) than those who didn't. Just remember, more isn't necessarily better -- and may leave you with steam coming out of your ears. A quarter teaspoon of red pepper flakes or a dash or hot pepper sauce (such as Tabasco) should do the trick. Other spices may help, too: "Anything that makes food more interesting, like paprika or garlic, will make you feel more satisfied so you're less likely to overeat," Crum says.

5. They snack

Trainer Valerie Waters has clients, including Jennifer Garner and Elizabeth Berkley, who tote 150-calorie snacks in coolers wherever they go. Favorite snack combos include apple slices and low-fat string cheese, a few crackers (like Wasa Crispbread) topped with chicken salad, or a few slices of rolled-up turkey and a handful of grapes. "It's really important to eat something, even if it's just 150 to 200 calories, every three to four hours," Waters says. "Your blood sugar can drop quickly, making you go from feeling kind of hungry to thinking, 'Omigod, if I don't eat now I will kill somebody.'"

Verdict: Try it.

"It's great to have snacks with you, so if you do suddenly become ravenous you're not tempted to grab the first high-cal thing you see," Taub-Dix says. Your best bet is a snack that contains a little bit of carbohydrate, to give you an energy boost, with some protein to make you feel satiated. And if you've got to have a sweet, trainer Rob Parr, whose clients have included Madonna and Naomi Watts, recommends this trick: Mix four ounces of fruit juice with four ounces of water, and blend it with a handful of berries or a banana. It's a 200-calorie smoothie. Health.com: More great convenience-food choices

6. They eat organic

Organic is all the rage in Hollywood. "The hormones in dairy, meat, and poultry raise estrogen levels, which can cause you to hold onto body fat," nutritionist Wiatt says. The pesticides on nonorganic fruits and veggies also inhibit hormonal activity in the body, leading to weight gain, claims trainer Kirsch, who has also worked with Heidi Klum. Another no-no: Anything that's processed or packaged, since it's often laden with preservatives and salt. "I encourage clients to eat as simply as possible -- for example, have just a plain chicken breast sautéed in a little lemon juice to add some flavor," says trainer Patrick Murphy, who works with Eva Longoria.

Verdict: Not going to hurt you, but ...

While it's definitely wise to avoid exposure to potentially harmful pesticides and eating organic can be healthy, there's no research to show that organic foods actually help with weight loss.

"Studies that look at the levels of hormones in people consuming conventional dairy products show pesticide levels are negligible," Crum says. Plus, "It's impossible to cut all sodium and refined sugars out of your diet even a plain chicken breast has some salt!" Taub-Dix says. "You shouldn't assume, either, that all packaged food is bad for you. There are some products, like the Kashi line, that are high in fiber and low in calories, fat, and salt."

7. They count backward

The 3-2-1 Baby Bulge Be Gone plan from Hollywood trainer Ramona Braganza helped both Jessica Alba and Halle Berry get back in prepregnancy shape. They ate three meals, had two snacks, and drank a minimum of 1 liter of water a day.

"Their meals were as lean and clean as possible they ate about 1,700 calories a day and completely avoided refined sugar, sauces, and sodium," Braganza says. Here's a sample of a day's menu: a breakfast of egg whites, strawberries, and whole-wheat toast; a snack of low-fat string cheese and almonds; a lunch of green salad topped with salmon; another snack of low-fat yogurt and fruit; and a dinner of baked chicken breast drizzled with lemon juice and mustard, paired with helping of vegetables. Alba met her H2O quotient with vitamin-enriched flavored water.

Verdict: Yes, but ...

"The only thing I would neg in this plan is the flavored water with vitamins -- it adds an extra 50 calories per bottle -- and if you're already taking a multivitamin, you may run the risk of overdoing it," Taub-Dix says. You can sub in a zero-calorie flavored water instead. Health.com: Seven under 75 holiday treats

8. They take ADD meds

Paris Hilton and a number of hot Hollywood actresses are reportedly using Adderall, the attention-deficit disorder (ADD) medication. In Paris' case, she says she takes it for ADD, which she has suffered from since she was 12. But the drug may have an added attraction: Adderall, a stimulant, was first marketed in the 1960s and 1970s as a diet pill because it decreases appetite and ramps up metabolism.

"Unfortunately, this drug is all too easy to get," says Scott Isaacs, M.D., an endocrinologist and obesity specialist at Emory University School of Medicine in Atlanta. "Anyone can walk into an unscrupulous doctor's office claiming she has ADD symptoms, such as difficulty concentrating and forgetfulness, and walk out with a prescription."

Verdict: Don't do it.

You shouldn't be taking this drug unless you're under a doctor's supervision, Isaacs says. Side effects include potentially dangerous increased blood pressure and heart rate. It's also been linked to problems such as hearing voices and maniacal behavior. If you're seriously overweight or obese, talk to your doctor about legitimate weight-loss drugs like Alli or phentermine.

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Ever since Beyoncé admitted to losing 20 pounds on the Master Cleanse -- a fast that usually involves at least 10 days of sipping nothing but an elixir of maple syrup, lemon juice, water, and cayenne pepper -- Hollywood has been buzzing about the weight-loss technique (also called the lemonade diet). The lemon supposedly acts as a purifier and provides bloat-reducing potassium, the cayenne pepper adds metabolism-boosting B vitamins, and the maple syrup provides the energy needed to get through such a grueling ordeal. "While I wouldn't recommend doing something so drastic for more than a few days, I can say it works if you want to quickly shed three to five pounds," Peterson says.

Another popular, less-dramatic cleanse is the 30-day Isagenix program, which involves eating about 1,000 calories a day in the form of shakes and snack bars that contain diuretics like aloe vera. Health.com: Three ways to burn off eggnog

Verdict: Not so fast.

"The first few days, you're just losing water weight, which is why you may see the scale drop so quickly," Taub-Dix says. "But it's counterproductive -- all this does is slow down your metabolism, so you're more apt to regain weight once you stop." The diuretics also dehydrate you, which is dangerous, especially if you're working out a lot. "You can become deficient in crucial minerals like sodium and potassium, which affect heart function," Crum says.